As a snowmobile travels over snow, the upturned front ends of the skis encounter stationary air and forces the air up and around the front portion of the skis. For each ski, this creates a low pressure turbulent region behind the upturned front portion which causes air behind the upturned front portion to move toward the center of the ski until it makes contact with a vertical longitudinally extending rib typically found on snowmobile skis. Due to the forward motion of the vehicle, the air then travels along the rib toward the rear of the ski and is passed by the rest of the snowmobile at approximately the width of the footrests because the footrest are laterally aligned with the skis.
As seen in FIG. 6, when a snowmobile 200 travels over a relatively hard packed undersurface that is covered by a thin layer of light snow, the light snow is displaced by the front of the ski 202 and is picked up by the airflow (indicated by lines 204) around the ski 202 and is also eventually passed by the rest of the snowmobile 200.
Protective components of the snowmobile 200 such as a windshield 206, hand guards, and side panel wind deflectors 208 create a low pressure region (schematically illustrated as area 210) around the driver area when moving forward. This low pressure region pulls the turbulent air and the snow traveling with it (indicated by lines 212) toward the driver area. Once the snow contacts the driver's feet and lower legs and/or other vehicle components around the driver's area, it sticks to them and over time, the driver's lower legs are fully covered in snow which is, as would be understood, cold and unpleasant.
In some skis, a head of a fastener used to connect the ski to the snowmobile protrudes from the rib. The head of the fastener causes the air traveling along the rib to lose speed (relative to the snowmobile).
When the snow carried by the air flow makes contact with the head of the fastener and becomes entrained in the turbulent air behind the front portion of the ski, the overall height of the flow from the ground increases and further contributes to the negative pressure area sucking snow toward the vehicle driver area where it is finally deposited onto the foot boards and around the driver's feet and lower legs.
The turbulence caused by the head of the fastener could be minimized by providing a cap on the head or by recessing the head of the fastener in the rib. However, the turbulence caused by the upturned front portion of the ski would still cause snow to deposit onto the foot boards and around the driver's feet and lower legs.
Therefore, there is a need for a snowmobile ski which at least reduces the amount of snow onto the foot boards and around the driver's feet and lower legs due to the air turbulence caused by the ski.